<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title>Headers</title><meta name="generator" content="DocBook XSL Stylesheets Vsnapshot" /><meta name="keywords" content="ISO C++, library" /><meta name="keywords" content="ISO C++, runtime, library" /><link rel="home" href="../index.html" title="The GNU C++ Library" /><link rel="up" href="using.html" title="Chapter 3. Using" /><link rel="prev" href="using.html" title="Chapter 3. Using" /><link rel="next" href="using_macros.html" title="Macros" /></head><body><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">Headers</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="using.html">Prev</a> </td><th width="60%" align="center">Chapter 3. Using</th><td width="20%" align="right"> <a accesskey="n" href="using_macros.html">Next</a></td></tr></table><hr /></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="manual.intro.using.headers"></a>Headers</h2></div></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="manual.intro.using.headers.all"></a>Header Files</h3></div></div></div><p>
     The C++ standard specifies the entire set of header files that
     must be available to all hosted implementations.  Actually, the
     word "files" is a misnomer, since the contents of the
     headers don't necessarily have to be in any kind of external
     file.  The only rule is that when one <code class="code">#include</code>s a
     header, the contents of that header become available, no matter
     how.
   </p><p>
   That said, in practice files are used.
   </p><p>
     There are two main types of include files: header files related
     to a specific version of the ISO C++ standard (called Standard
     Headers), and all others (TS, TR1, C++ ABI, and Extensions).
   </p><p>
     Multiple dialects of standard headers are supported, corresponding to
     the 1998 standard as updated for 2003, the 2011 standard, the 2014
     standard, and so on.
   </p><p>
     <a class="xref" href="using_headers.html#table.cxx98_headers" title="Table 3.2. C++ 1998 Library Headers">Table 3.2, “C++ 1998 Library Headers”</a> and
     <a class="xref" href="using_headers.html#table.cxx98_cheaders" title="Table 3.3. C++ 1998 Library Headers for C Library Facilities">Table 3.3, “C++ 1998 Library Headers for C Library Facilities”</a> and
     <a class="xref" href="using_headers.html#table.cxx98_deprheaders" title="Table 3.4. C++ 1998 Deprecated Library Header">Table 3.4, “C++ 1998 Deprecated Library Header”</a>
     show the C++98/03 include files.
     These are available in the C++98 compilation mode,
     i.e. <code class="code">-std=c++98</code> or <code class="code">-std=gnu++98</code>.
     Unless specified otherwise below, they are also available in later modes
     (C++11, C++14 etc).
   </p><div class="table"><a id="table.cxx98_headers"></a><p class="title"><strong>Table 3.2. C++ 1998 Library Headers</strong></p><div class="table-contents"><table class="table" summary="C++ 1998 Library Headers" border="1"><colgroup><col align="left" class="c1" /><col align="left" class="c2" /><col align="left" class="c3" /><col align="left" class="c4" /><col align="left" class="c5" /></colgroup><tbody><tr><td align="left"><code class="filename">algorithm</code></td><td align="left"><code class="filename">bitset</code></td><td align="left"><code class="filename">complex</code></td><td align="left"><code class="filename">deque</code></td><td align="left"><code class="filename">exception</code></td></tr><tr><td align="left"><code class="filename">fstream</code></td><td align="left"><code class="filename">functional</code></td><td align="left"><code class="filename">iomanip</code></td><td align="left"><code class="filename">ios</code></td><td align="left"><code class="filename">iosfwd</code></td></tr><tr><td align="left"><code class="filename">iostream</code></td><td align="left"><code class="filename">istream</code></td><td align="left"><code class="filename">iterator</code></td><td align="left"><code class="filename">limits</code></td><td align="left"><code class="filename">list</code></td></tr><tr><td align="left"><code class="filename">locale</code></td><td align="left"><code class="filename">map</code></td><td align="left"><code class="filename">memory</code></td><td align="left"><code class="filename">new</code></td><td align="left"><code class="filename">numeric</code></td></tr><tr><td align="left"><code class="filename">ostream</code></td><td align="left"><code class="filename">queue</code></td><td align="left"><code class="filename">set</code></td><td align="left"><code class="filename">sstream</code></td><td align="left"><code class="filename">stack</code></td></tr><tr><td align="left"><code class="filename">stdexcept</code></td><td align="left"><code class="filename">streambuf</code></td><td align="left"><code class="filename">string</code></td><td align="left"><code class="filename">utility</code></td><td align="left"><code class="filename">typeinfo</code></td></tr><tr><td align="left"><code class="filename">valarray</code></td><td align="left"><code class="filename">vector</code></td><td colspan="3" align="left"> </td></tr></tbody></table></div></div><br class="table-break" /><p></p><div class="table"><a id="table.cxx98_cheaders"></a><p class="title"><strong>Table 3.3. C++ 1998 Library Headers for C Library Facilities</strong></p><div class="table-contents"><table class="table" summary="C++ 1998 Library Headers for C Library Facilities" border="1"><colgroup><col align="left" class="c1" /><col align="left" class="c2" /><col align="left" class="c3" /><col align="left" class="c4" /><col align="left" class="c5" /></colgroup><tbody><tr><td align="left"><code class="filename">cassert</code></td><td align="left"><code class="filename">cerrno</code></td><td align="left"><code class="filename">cctype</code></td><td align="left"><code class="filename">cfloat</code></td><td align="left"><code class="filename">ciso646</code></td></tr><tr><td align="left"><code class="filename">climits</code></td><td align="left"><code class="filename">clocale</code></td><td align="left"><code class="filename">cmath</code></td><td align="left"><code class="filename">csetjmp</code></td><td align="left"><code class="filename">csignal</code></td></tr><tr><td align="left"><code class="filename">cstdarg</code></td><td align="left"><code class="filename">cstddef</code></td><td align="left"><code class="filename">cstdio</code></td><td align="left"><code class="filename">cstdlib</code></td><td align="left"><code class="filename">cstring</code></td></tr><tr><td align="left"><code class="filename">ctime</code></td><td align="left"><code class="filename">cwchar</code></td><td align="left"><code class="filename">cwctype</code></td><td colspan="2" align="left"> </td></tr></tbody></table></div></div><br class="table-break" /><p>
  The following header is deprecated
  and might be removed from a future C++ standard.
</p><div class="table"><a id="table.cxx98_deprheaders"></a><p class="title"><strong>Table 3.4. C++ 1998 Deprecated Library Header</strong></p><div class="table-contents"><table class="table" summary="C++ 1998 Deprecated Library Header" border="1"><colgroup><col align="left" class="c1" /></colgroup><tbody><tr><td align="left"><code class="filename">strstream</code></td></tr></tbody></table></div></div><br class="table-break" /><p>
<a class="xref" href="using_headers.html#table.cxx11_headers" title="Table 3.5. C++ 2011 Library Headers">Table 3.5, “C++ 2011 Library Headers”</a> and
<a class="xref" href="using_headers.html#table.cxx11_cheaders" title="Table 3.6. C++ 2011 Library Headers for C Library Facilities">Table 3.6, “C++ 2011 Library Headers for C Library Facilities”</a> show the C++11 include files.
These are available in C++11 compilation
mode, i.e. <code class="literal">-std=c++11</code> or <code class="literal">-std=gnu++11</code>.
Including these headers in C++98/03 mode may result in compilation errors.
Unless specified otherwise below, they are also available in later modes
(C++14 etc).
</p><p></p><div class="table"><a id="table.cxx11_headers"></a><p class="title"><strong>Table 3.5. C++ 2011 Library Headers</strong></p><div class="table-contents"><table class="table" summary="C++ 2011 Library Headers" border="1"><colgroup><col align="left" class="c1" /><col align="left" class="c2" /><col align="left" class="c3" /><col align="left" class="c4" /><col align="left" class="c5" /></colgroup><tbody><tr><td align="left"><code class="filename">array</code></td><td align="left"><code class="filename">atomic</code></td><td align="left"><code class="filename">chrono</code></td><td align="left"><code class="filename">codecvt</code></td><td align="left"><code class="filename">condition_variable</code></td></tr><tr><td align="left"><code class="filename">forward_list</code></td><td align="left"><code class="filename">future</code></td><td align="left"><code class="filename">initalizer_list</code></td><td align="left"><code class="filename">mutex</code></td><td align="left"><code class="filename">random</code></td></tr><tr><td align="left"><code class="filename">ratio</code></td><td align="left"><code class="filename">regex</code></td><td align="left"><code class="filename">scoped_allocator</code></td><td align="left"><code class="filename">system_error</code></td><td align="left"><code class="filename">thread</code></td></tr><tr><td align="left"><code class="filename">tuple</code></td><td align="left"><code class="filename">typeindex</code></td><td align="left"><code class="filename">type_traits</code></td><td align="left"><code class="filename">unordered_map</code></td><td align="left"><code class="filename">unordered_set</code></td></tr></tbody></table></div></div><br class="table-break" /><p></p><div class="table"><a id="table.cxx11_cheaders"></a><p class="title"><strong>Table 3.6. C++ 2011 Library Headers for C Library Facilities</strong></p><div class="table-contents"><table class="table" summary="C++ 2011 Library Headers for C Library Facilities" border="1"><colgroup><col align="left" class="c1" /><col align="left" class="c2" /><col align="left" class="c3" /><col align="left" class="c4" /><col align="left" class="c5" /></colgroup><tbody><tr><td align="left"><code class="filename">ccomplex</code></td><td align="left"><code class="filename">cfenv</code></td><td align="left"><code class="filename">cinttypes</code></td><td align="left"><code class="filename">cstdalign</code></td><td align="left"><code class="filename">cstdbool</code></td></tr><tr><td align="left"><code class="filename">cstdint</code></td><td align="left"><code class="filename">ctgmath</code></td><td align="left"><code class="filename">cuchar</code></td><td colspan="2" align="left"> </td></tr></tbody></table></div></div><br class="table-break" /><p>
<a class="xref" href="using_headers.html#table.cxx14_headers" title="Table 3.7. C++ 2014 Library Header">Table 3.7, “C++ 2014 Library Header”</a> shows the C++14 include file.
This is available in C++14 compilation
mode, i.e. <code class="literal">-std=c++14</code> or <code class="literal">-std=gnu++14</code>.
Including this header in C++98/03 mode or C++11 will not result in
compilation errors, but will not define anything.
Unless specified otherwise below, it is also available in later modes
(C++17 etc).
</p><p></p><div class="table"><a id="table.cxx14_headers"></a><p class="title"><strong>Table 3.7. C++ 2014 Library Header</strong></p><div class="table-contents"><table class="table" summary="C++ 2014 Library Header" border="1"><colgroup><col align="left" class="c1" /></colgroup><tbody><tr><td align="left"><code class="filename">shared_mutex</code></td></tr></tbody></table></div></div><br class="table-break" /><p>
<a class="xref" href="using_headers.html#table.cxx17_headers" title="Table 3.8. C++ 2017 Library Headers">Table 3.8, “C++ 2017 Library Headers”</a> shows the C++17 include files.
These are available in C++17 compilation
mode, i.e. <code class="literal">-std=c++17</code> or <code class="literal">-std=gnu++17</code>.
Including these headers in earlier modes will not result in
compilation errors, but will not define anything.
Unless specified otherwise below, they are also available in later modes
(C++20 etc).
</p><p></p><div class="table"><a id="table.cxx17_headers"></a><p class="title"><strong>Table 3.8. C++ 2017 Library Headers</strong></p><div class="table-contents"><table class="table" summary="C++ 2017 Library Headers" border="1"><colgroup><col align="left" class="c1" /><col align="left" class="c2" /><col align="left" class="c3" /><col align="left" class="c4" /><col align="left" class="c5" /></colgroup><tbody><tr><td align="left"><code class="filename">any</code></td><td align="left"><code class="filename">charconv</code></td><td align="left"><code class="filename">execution</code></td><td align="left"><code class="filename">filesystem</code></td><td align="left"><code class="filename">memory_resource</code></td></tr><tr><td align="left"><code class="filename">optional</code></td><td align="left"><code class="filename">string_view</code></td><td align="left"><code class="filename">variant</code></td><td colspan="2" align="left"> </td></tr></tbody></table></div></div><br class="table-break" /><p>
<a class="xref" href="using_headers.html#table.cxx20_headers" title="Table 3.9. C++ 2020 Library Headers">Table 3.9, “C++ 2020 Library Headers”</a>
shows the C++2a include files.
These are available in C++2a compilation
mode, i.e. <code class="literal">-std=c++2a</code> or <code class="literal">-std=gnu++2a</code>.
Including these headers in earlier modes will not result in
compilation errors, but will not define anything.

</p><p></p><div class="table"><a id="table.cxx20_headers"></a><p class="title"><strong>Table 3.9. C++ 2020 Library Headers</strong></p><div class="table-contents"><table class="table" summary="C++ 2020 Library Headers" border="1"><colgroup><col align="left" class="c1" /><col align="left" class="c2" /></colgroup><tbody><tr><td align="left"><code class="filename">bit</code></td><td align="left"><code class="filename">version</code></td></tr></tbody></table></div></div><br class="table-break" /><p>
  The following headers have been removed in the C++2a working draft.
  They are still available when using this implementation, but in future
  they might start to produce warnings or errors when included in C++2a mode.
  Programs that intend to be portable should not include them.
</p><div class="table"><a id="table.cxx20_deprheaders"></a><p class="title"><strong>Table 3.10. C++ 2020 Obsolete Headers</strong></p><div class="table-contents"><table class="table" summary="C++ 2020 Obsolete Headers" border="1"><colgroup><col align="left" class="c1" /><col align="left" class="c2" /><col align="left" class="c3" /><col align="left" class="c4" /><col align="left" class="c5" /></colgroup><tbody><tr><td align="left"><code class="filename">ccomplex</code></td><td align="left"><code class="filename">ciso646</code></td><td align="left"><code class="filename">cstdalign</code></td><td align="left"><code class="filename">cstdbool</code></td><td align="left"><code class="filename">ctgmath</code></td></tr></tbody></table></div></div><br class="table-break" /><p>
<a class="xref" href="using_headers.html#table.filesystemts_headers" title="Table 3.11. File System TS Header">Table 3.11, “File System TS Header”</a>,
shows the additional include file define by the
File System Technical Specification, ISO/IEC TS 18822.
This is available in C++11 and later compilation modes.
Including this header in earlier modes will not result in
compilation errors, but will not define anything.
</p><p></p><div class="table"><a id="table.filesystemts_headers"></a><p class="title"><strong>Table 3.11. File System TS Header</strong></p><div class="table-contents"><table class="table" summary="File System TS Header" border="1"><colgroup><col align="left" class="c1" /></colgroup><tbody><tr><td align="left"><code class="filename">experimental/filesystem</code></td></tr></tbody></table></div></div><br class="table-break" /><p>
<a class="xref" href="using_headers.html#table.libfundts_headers" title="Table 3.12. Library Fundamentals TS Headers">Table 3.12, “Library Fundamentals TS Headers”</a>,
shows the additional include files define by the C++ Extensions for
Library Fundamentals Technical Specification, ISO/IEC TS 19568.
These are available in C++14 and later compilation modes.
Including these headers in earlier modes will not result in
compilation errors, but will not define anything.
</p><p></p><div class="table"><a id="table.libfundts_headers"></a><p class="title"><strong>Table 3.12. Library Fundamentals TS Headers</strong></p><div class="table-contents"><table class="table" summary="Library Fundamentals TS Headers" border="1"><colgroup><col align="left" class="c1" /><col align="left" class="c2" /><col align="left" class="c3" /><col align="left" class="c4" /><col align="left" class="c5" /></colgroup><tbody><tr><td align="left"><code class="filename">experimental/algorithm</code></td><td align="left"><code class="filename">experimental/any</code></td><td align="left"><code class="filename">experimental/array</code></td><td align="left"><code class="filename">experimental/chrono</code></td><td align="left"><code class="filename">experimental/deque</code></td></tr><tr><td align="left"><code class="filename">experimental/forward_list</code></td><td align="left"><code class="filename">experimental/functional</code></td><td align="left"><code class="filename">experimental/iterator</code></td><td align="left"><code class="filename">experimental/list</code></td><td align="left"><code class="filename">experimental/map</code></td></tr><tr><td align="left"><code class="filename">experimental/memory</code></td><td align="left"><code class="filename">experimental/memory_resource</code></td><td align="left"><code class="filename">experimental/numeric</code></td><td align="left"><code class="filename">experimental/optional</code></td><td align="left"><code class="filename">experimental/propagate_const</code></td></tr><tr><td align="left"><code class="filename">experimental/random</code></td><td align="left"><code class="filename">experimental/ratio</code></td><td align="left"><code class="filename">experimental/regex</code></td><td align="left"><code class="filename">experimental/set</code></td><td align="left"><code class="filename">experimental/source_location</code></td></tr><tr><td align="left"><code class="filename">experimental/string</code></td><td align="left"><code class="filename">experimental/string_view</code></td><td align="left"><code class="filename">experimental/system_error</code></td><td align="left"><code class="filename">experimental/tuple</code></td><td align="left"><code class="filename">experimental/type_traits</code></td></tr><tr><td align="left"><code class="filename">experimental/unordered_map</code></td><td align="left"><code class="filename">experimental/unordered_set</code></td><td align="left"><code class="filename">experimental/utility</code></td><td align="left"><code class="filename">experimental/vector</code></td><td align="left"> </td></tr></tbody></table></div></div><br class="table-break" /><p>
  In addition, TR1 includes as:
</p><div class="table"><a id="table.tr1_headers"></a><p class="title"><strong>Table 3.13. C++ TR 1 Library Headers</strong></p><div class="table-contents"><table class="table" summary="C++ TR 1 Library Headers" border="1"><colgroup><col align="left" class="c1" /><col align="left" class="c2" /><col align="left" class="c3" /><col align="left" class="c4" /><col align="left" class="c5" /></colgroup><tbody><tr><td align="left"><code class="filename">tr1/array</code></td><td align="left"><code class="filename">tr1/complex</code></td><td align="left"><code class="filename">tr1/memory</code></td><td align="left"><code class="filename">tr1/functional</code></td><td align="left"><code class="filename">tr1/random</code></td></tr><tr><td align="left"><code class="filename">tr1/regex</code></td><td align="left"><code class="filename">tr1/tuple</code></td><td align="left"><code class="filename">tr1/type_traits</code></td><td align="left"><code class="filename">tr1/unordered_map</code></td><td align="left"><code class="filename">tr1/unordered_set</code></td></tr><tr><td align="left"><code class="filename">tr1/utility</code></td><td colspan="4" align="left"> </td></tr></tbody></table></div></div><br class="table-break" /><p></p><div class="table"><a id="table.tr1_cheaders"></a><p class="title"><strong>Table 3.14. C++ TR 1 Library Headers for C Library Facilities</strong></p><div class="table-contents"><table class="table" summary="C++ TR 1 Library Headers for C Library Facilities" border="1"><colgroup><col align="left" class="c1" /><col align="left" class="c2" /><col align="left" class="c3" /><col align="left" class="c4" /><col align="left" class="c5" /></colgroup><tbody><tr><td align="left"><code class="filename">tr1/ccomplex</code></td><td align="left"><code class="filename">tr1/cfenv</code></td><td align="left"><code class="filename">tr1/cfloat</code></td><td align="left"><code class="filename">tr1/cmath</code></td><td align="left"><code class="filename">tr1/cinttypes</code></td></tr><tr><td align="left"><code class="filename">tr1/climits</code></td><td align="left"><code class="filename">tr1/cstdarg</code></td><td align="left"><code class="filename">tr1/cstdbool</code></td><td align="left"><code class="filename">tr1/cstdint</code></td><td align="left"><code class="filename">tr1/cstdio</code></td></tr><tr><td align="left"><code class="filename">tr1/cstdlib</code></td><td align="left"><code class="filename">tr1/ctgmath</code></td><td align="left"><code class="filename">tr1/ctime</code></td><td align="left"><code class="filename">tr1/cwchar</code></td><td align="left"><code class="filename">tr1/cwctype</code></td></tr></tbody></table></div></div><br class="table-break" /><p>Decimal floating-point arithmetic is available if the C++
compiler supports scalar decimal floating-point types defined via
<code class="code">__attribute__((mode(SD|DD|LD)))</code>.
</p><div class="table"><a id="table.decfp_headers"></a><p class="title"><strong>Table 3.15. C++ TR 24733 Decimal Floating-Point Header</strong></p><div class="table-contents"><table class="table" summary="C++ TR 24733 Decimal Floating-Point Header" border="1"><colgroup><col align="left" class="c1" /></colgroup><tbody><tr><td align="left"><code class="filename">decimal/decimal</code></td></tr></tbody></table></div></div><br class="table-break" /><p>
  Also included are files for the C++ ABI interface:
</p><div class="table"><a id="table.abi_headers"></a><p class="title"><strong>Table 3.16. C++ ABI Headers</strong></p><div class="table-contents"><table class="table" summary="C++ ABI Headers" border="1"><colgroup><col align="left" class="c1" /><col align="left" class="c2" /></colgroup><tbody><tr><td align="left"><code class="filename">cxxabi.h</code></td><td align="left"><code class="filename">cxxabi_forced.h</code></td></tr></tbody></table></div></div><br class="table-break" /><p>
  And a large variety of extensions.
</p><div class="table"><a id="table.ext_headers"></a><p class="title"><strong>Table 3.17. Extension Headers</strong></p><div class="table-contents"><table class="table" summary="Extension Headers" border="1"><colgroup><col align="left" class="c1" /><col align="left" class="c2" /><col align="left" class="c3" /><col align="left" class="c4" /><col align="left" class="c5" /></colgroup><tbody><tr><td align="left"><code class="filename">ext/algorithm</code></td><td align="left"><code class="filename">ext/atomicity.h</code></td><td align="left"><code class="filename">ext/bitmap_allocator.h</code></td><td align="left"><code class="filename">ext/cast.h</code></td><td class="auto-generated"> </td></tr><tr><td align="left"><code class="filename">ext/codecvt_specializations.h</code></td><td align="left"><code class="filename">ext/concurrence.h</code></td><td align="left"><code class="filename">ext/debug_allocator.h</code></td><td align="left"><code class="filename">ext/enc_filebuf.h</code></td><td align="left"><code class="filename">ext/extptr_allocator.h</code></td></tr><tr><td align="left"><code class="filename">ext/functional</code></td><td align="left"><code class="filename">ext/iterator</code></td><td align="left"><code class="filename">ext/malloc_allocator.h</code></td><td align="left"><code class="filename">ext/memory</code></td><td align="left"><code class="filename">ext/mt_allocator.h</code></td></tr><tr><td align="left"><code class="filename">ext/new_allocator.h</code></td><td align="left"><code class="filename">ext/numeric</code></td><td align="left"><code class="filename">ext/numeric_traits.h</code></td><td align="left"><code class="filename">ext/pb_ds/assoc_container.h</code></td><td align="left"><code class="filename">ext/pb_ds/priority_queue.h</code></td></tr><tr><td align="left"><code class="filename">ext/pod_char_traits.h</code></td><td align="left"><code class="filename">ext/pool_allocator.h</code></td><td align="left"><code class="filename">ext/rb_tree</code></td><td align="left"><code class="filename">ext/rope</code></td><td align="left"><code class="filename">ext/slist</code></td></tr><tr><td align="left"><code class="filename">ext/stdio_filebuf.h</code></td><td align="left"><code class="filename">ext/stdio_sync_filebuf.h</code></td><td align="left"><code class="filename">ext/throw_allocator.h</code></td><td align="left"><code class="filename">ext/typelist.h</code></td><td align="left"><code class="filename">ext/type_traits.h</code></td></tr><tr><td align="left"><code class="filename">ext/vstring.h</code></td><td colspan="4" align="left"> </td></tr></tbody></table></div></div><br class="table-break" /><p></p><div class="table"><a id="table.debug_headers"></a><p class="title"><strong>Table 3.18. Extension Debug Headers</strong></p><div class="table-contents"><table class="table" summary="Extension Debug Headers" border="1"><colgroup><col align="left" class="c1" /><col align="left" class="c2" /><col align="left" class="c3" /><col align="left" class="c4" /><col align="left" class="c5" /></colgroup><tbody><tr><td align="left"><code class="filename">debug/array</code></td><td align="left"><code class="filename">debug/bitset</code></td><td align="left"><code class="filename">debug/deque</code></td><td align="left"><code class="filename">debug/forward_list</code></td><td align="left"><code class="filename">debug/list</code></td></tr><tr><td align="left"><code class="filename">debug/map</code></td><td align="left"><code class="filename">debug/set</code></td><td align="left"><code class="filename">debug/string</code></td><td align="left"><code class="filename">debug/unordered_map</code></td><td align="left"><code class="filename">debug/unordered_set</code></td></tr><tr><td align="left"><code class="filename">debug/vector</code></td><td colspan="4" align="left"> </td></tr></tbody></table></div></div><br class="table-break" /><p></p><div class="table"><a id="table.parallel_headers"></a><p class="title"><strong>Table 3.19. Extension Parallel Headers</strong></p><div class="table-contents"><table class="table" summary="Extension Parallel Headers" border="1"><colgroup><col align="left" class="c1" /><col align="left" class="c2" /></colgroup><tbody><tr><td align="left"><code class="filename">parallel/algorithm</code></td><td align="left"><code class="filename">parallel/numeric</code></td></tr></tbody></table></div></div><br class="table-break" /></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="manual.intro.using.headers.mixing"></a>Mixing Headers</h3></div></div></div><p> A few simple rules.
</p><p>First, mixing different dialects of the standard headers is not
possible. It's an all-or-nothing affair. Thus, code like
</p><pre class="programlisting">
#include &lt;array&gt;
#include &lt;functional&gt;
</pre><p>Implies C++11 mode. To use the entities in &lt;array&gt;, the C++11
compilation mode must be used, which implies the C++11 functionality
(and deprecations) in &lt;functional&gt; will be present.
</p><p>Second, the other headers can be included with either dialect of
the standard headers, although features and types specific to C++11
are still only enabled when in C++11 compilation mode. So, to use
rvalue references with <code class="code">__gnu_cxx::vstring</code>, or to use the
debug-mode versions of <code class="code">std::unordered_map</code>, one must use
the <code class="code">std=gnu++11</code> compiler flag. (Or <code class="code">std=c++11</code>, of course.)
</p><p>A special case of the second rule is the mixing of TR1 and C++11
facilities. It is possible (although not especially prudent) to
include both the TR1 version and the C++11 version of header in the
same translation unit:
</p><pre class="programlisting">
#include &lt;tr1/type_traits&gt;
#include &lt;type_traits&gt;
</pre><p> Several parts of C++11 diverge quite substantially from TR1 predecessors.
</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="manual.intro.using.headers.cheaders"></a>The C Headers and <code class="code">namespace std</code></h3></div></div></div><p>
	The standard specifies that if one includes the C-style header
	(&lt;math.h&gt; in this case), the symbols will be available
	in the global namespace and perhaps in
	namespace <code class="code">std::</code> (but this is no longer a firm
	requirement.) On the other hand, including the C++-style
	header (&lt;cmath&gt;) guarantees that the entities will be
	found in namespace std and perhaps in the global namespace.
      </p><p>
Usage of C++-style headers is recommended, as then
C-linkage names can be disambiguated by explicit qualification, such
as by <code class="code">std::abort</code>. In addition, the C++-style headers can
use function overloading to provide a simpler interface to certain
families of C-functions. For instance in &lt;cmath&gt;, the
function <code class="code">std::sin</code> has overloads for all the builtin
floating-point types. This means that <code class="code">std::sin</code> can be
used uniformly, instead of a combination
of <code class="code">std::sinf</code>, <code class="code">std::sin</code>,
and <code class="code">std::sinl</code>.
</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="manual.intro.using.headers.pre"></a>Precompiled Headers</h3></div></div></div><p>There are three base header files that are provided. They can be
used to precompile the standard headers and extensions into binary
files that may then be used to speed up compilations that use these headers.
</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><p>stdc++.h</p><p>Includes all standard headers. Actual content varies depending on
<a class="link" href="using.html#manual.intro.using.flags" title="Command Options">language dialect</a>.
</p></li><li class="listitem"><p>stdtr1c++.h</p><p>Includes all of &lt;stdc++.h&gt;, and adds all the TR1 headers.
</p></li><li class="listitem"><p>extc++.h</p><p>Includes all of &lt;stdc++.h&gt;, and adds all the Extension headers
(and in C++98 mode also adds all the TR1 headers by including all of
&lt;stdtr1c++.h&gt;).
</p></li></ul></div><p>To construct a .gch file from one of these base header files,
first find the include directory for the compiler. One way to do
this is:</p><pre class="programlisting">
g++ -v hello.cc

#include &lt;...&gt; search starts here:
 /mnt/share/bld/H-x86-gcc.20071201/include/c++/4.3.0
...
End of search list.
</pre><p>Then, create a precompiled header file with the same flags that
will be used to compile other projects.</p><pre class="programlisting">
g++ -Winvalid-pch -x c++-header -g -O2 -o ./stdc++.h.gch /mnt/share/bld/H-x86-gcc.20071201/include/c++/4.3.0/x86_64-unknown-linux-gnu/bits/stdc++.h
</pre><p>The resulting file will be quite large: the current size is around
thirty megabytes. </p><p>How to use the resulting file.</p><pre class="programlisting">
g++ -I. -include stdc++.h  -H -g -O2 hello.cc
</pre><p>Verification that the PCH file is being used is easy:</p><pre class="programlisting">
g++ -Winvalid-pch -I. -include stdc++.h -H -g -O2 hello.cc -o test.exe
! ./stdc++.h.gch
. /mnt/share/bld/H-x86-gcc.20071201/include/c++/4.3.0/iostream
. /mnt/share/bld/H-x86-gcc.20071201include/c++/4.3.0/string
</pre><p>The exclamation point to the left of the <code class="code">stdc++.h.gch</code> listing means that the generated PCH file was used.</p><p></p><p> Detailed information about creating precompiled header files can be found in the GCC <a class="link" href="http://gcc.gnu.org/onlinedocs/gcc/Precompiled-Headers.html" target="_top">documentation</a>.
</p></div></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="using.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="using.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="using_macros.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">Chapter 3. Using </td><td width="20%" align="center"><a accesskey="h" href="../index.html">Home</a></td><td width="40%" align="right" valign="top"> Macros</td></tr></table></div></body></html>